Abstract: In order to make full use of the mineral resources of Mirador North Mine，reduce the amount of rock stripping，improve the utilization rate of resources and the economic benefits of the mine， the NPV optimization program is used to optimize the open-pit mining boundary of Mirador North Mine. Based on the technical and economic parameters，the final slope angle and other main parameters of Mira‐ dor South Mine，the main parameters of Mirador North Mine boundary optimization are determined. Ac‐ cording to the constructed model，a total of 41 boundaries are delineated，and the incremental value and cumulative value of the NPV open-pit optimization boundary are obtained，and the change trend is ana‐ lyzed. The results show that after the Pit31 boundary，the net present value increment becomes negative， the cumulative value of the net present value is the largest，and the Pit31 boundary is the optimal reference boundary. The amount of ore in the boundary is not sensitive to the rise of metal price，but very sensitive to the decline of metal price. The maximum elevation of the optimized boundary stope is 1 135 m，the elevation of the closed ring is 900 m，the bottom elevation of the open-pit mine is 510 m，the mining depth is 390 m，and the mining height is 235 m. The amount of ore in the boundary increased by 59.286 million tons， with an increase of 2%，and the average grade of the increased ore is 0.385%，which extend the service life of the mine and ensure the full development and utilization of mineral resources.

Key words: Mirador open-pit mine, NPV optimization program, mining boundary, sensitivity analysis